Drilling boreholes in the earth, for oil wells for example, involves the use of drilling mud and generates drill cuttings. Drilling muds, or fluids, typically comprise: a base fluid (such as water, oil, or a synthetic compound); weighting agents (such as barium sulfate); bentonite clay to help remove cuttings from the well and to form a filter cake on the walls of the borehole; lignosulfonates and lignites to keep the mud in a fluid state; and various additives, as required. Drill cuttings are solids removed from the borehole while drilling the well. Although sand and shale make up the majority of cuttings for oil wells, depending on the location, other geological formations may be encountered. Drill cuttings are usually removed from the drilling mud by flowing the drilling mud over shale shakers. Multiple shale shakers with progressively finer mesh screens may be used to remove enough of the drill cuttings to permit reuse of the drilling mud. However, in some circumstances, after flowing over shale shakers the drilling mud may still retain too many fine particulates for reuse.
After separation from the drilling mud in a shale shaker, the drill cuttings often retain a significant amount of drilling mud, which it may be desirable to recover. Furthermore, it may be necessary to recover some of the drilling mud from the drill cuttings before the drill cuttings can be properly disposed of according to local environmental regulations. There is a need for efficient methods and equipment for recovery of drilling mud from drill cuttings.
When drilling mud becomes too contaminated, or it is no longer needed, it must be reclaimed or disposed of in a way that satisfies local environmental regulations. To satisfy these regulations, and/or to reduce the weight of material that must be hauled off to certified disposal facilities, processing of the drilling mud may be necessary. This processing may include dewatering of the drilling mud. There is a need for efficient methods and equipment for dewatering of drilling mud.
In conclusion, there is a need for environmentally friendly methods of disposing of drill cuttings and drilling muds, and for equipment for implementing these methods.